LIGHT EMITTING DIODE CHIP HAVING DISTRIBUTED BRAGG REFLECTOR AND METHOD OF FABRICATING THE SAME

• US 20110127549A1
• Filed: 02/09/2011
• Published: 06/02/2011
• Est. Priority Date: 11/13/2009
• Status: Active Grant

• Current Assignee: Seoul Viosys Co., Ltd. (Seoul Semiconductor Co., Ltd.)
• Original Assignee: Seoul Optodevice Company Limited (Seoul Semiconductor Co., Ltd.)
• Inventors: KIM, Jong Kyu, JIN, Sang Ki, SHIN, Jin Cheol, LEE, So Ra, LEE, Sum Geun
• Granted Patent: US 8,963,178 B2
• Time in Patent Office: Days
• US Class Current: 257/88
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 27/153 in a repetitive configuration, e.g. LED bars
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2933/0025 relating to coatings
• CPC Class Codes: H01L 2933/0033 relating to semiconductor body packages
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/0058 relating to optical field-shaping elements
• CPC Class Codes: H01L 33/0008 having p-n or hi-lo junctions
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

Exemplary embodiments of the present invention disclose a light emitting diode chip including a substrate having a first surface and a second surface, a light emitting structure arranged on the first surface of the substrate and including an active layer arranged between a first conductive-type semiconductor layer and a second conductive-type semiconductor layer, a distributed Bragg reflector arranged on the second surface of the substrate, the distributed Bragg reflector to reflect light emitted from the light emitting structure, and a metal layer arranged on the distributed Bragg reflector, wherein the distributed Bragg reflector has a reflectivity of at least 90% for light of a first wavelength in a blue wavelength range, light of a second wavelength in a green wavelength range, and light of a third wavelength in a red wavelength range.

Claims

1. A light emitting diode chip, comprising:

a substrate comprising a first surface and a second surface;

a light emitting structure arranged on the first surface of the substrate, the light emitting structure comprising an active layer arranged between a first conductive-type semiconductor layer and a second conductive-type semiconductor layer;

a distributed Bragg reflector arranged on the second surface of the substrate, the distributed Bragg reflector to reflect light emitted from the light emitting structure; and

a metal layer arranged on the distributed Bragg reflector,

wherein the distributed Bragg reflector comprises a reflectivity of at least 90% for light of a first wavelength in a blue wavelength range, light of a second wavelength in a green wavelength range, and light of a third wavelength in a red wavelength range.

2. The light emitting diode chip of claim 1, wherein the metal layer comprises a reflective metal layer.

3. The light emitting diode chip of claim 2, wherein the reflective metal layer comprises Al.

4. The light emitting diode chip of claim 1, wherein the second surface of the substrate comprises a surface roughness comprising a root-mean-square (RMS) value of 3 nm or less.

5. The light emitting diode chip of claim 4, wherein the second surface of the substrate is surface treated and comprises a surface roughness comprising an RMS value of 1 nm or less.

6. The light emitting diode chip of claim 1, further comprising a plurality of light emitting cells arranged on the substrate.

7. The light emitting diode chip of claim 6, further comprising at least one light emitting cell array in which a portion of the plurality of light emitting cells are connected in series.

8. The light emitting diode chip of claim 6, further comprising a wire connecting adjacent light emitting cells in series,

wherein the plurality of light emitting cells comprise inclined side surfaces, and

the wire is connected to an inclined side surface of a first conductive-type semiconductor layer of one of the adjacent light emitting cells.

9. The light emitting diode chip of claim 1, wherein the distributed Bragg reflector comprises:

a first distributed Bragg reflector comprising higher reflectivity for light of the green wavelength range or the red wavelength range than for light of the blue wavelength range, and

a second distributed Bragg reflector comprising higher reflectivity for light of the blue wavelength range than for light of the red wavelength range.

10. The light emitting diode chip of claim 1, wherein the distributed Bragg reflector comprises a structure in which layers comprising different refractive indices are alternately stacked and the optical thickness of each alternating layer is different from each other.

11. The light emitting diode chip of claim 1, wherein the distributed Bragg reflector comprises a reflectivity of 98% or more at an incident angle of 0°

for light of all wavelengths within a range of 400 nm to 700 nm.

12. The light emitting diode chip of claim 1, wherein the distributed Bragg reflector comprises a reflectivity of 95% or more at an incident angle of 50°

for light of 700 nm.

13. A method of fabricating a light emitting diode chip, the method comprising:

forming a light emitting structure on a first surface of a substrate, the light emitting structure comprising;

a first conductive-type semiconductor layer;

a second conductive-type semiconductor layer; and

an active layer disposed between the first conductive-type semiconductor layer and the second conductive-type semiconductor layer;

removing a portion of the substrate by grinding a second surface of the substrate;

after the grinding, reducing the surface roughness of the second surface of the substrate by lapping the substrate; and

forming a distributed Bragg reflector on the second surface of the substrate.

14. The method of claim 13, further comprising forming a reflective metal layer or a protective layer on the distributed Bragg reflector.

15. The method of claim 13, wherein the surface roughness of the second surface of the substrate comprises a root-mean-square (RMS) value of 3 nm or less before forming the distributed Bragg reflector.

16. The method of claim 13, wherein the distributed Bragg reflector comprises a reflectivity of at least 90% for light of a first wavelength in a blue wavelength range, light of a second wavelength in a green wavelength range, and light of a third wavelength in a red wavelength range.

17. The method of claim 13, wherein the surface roughness of the second surface of the substrate comprises a root-mean-square (RMS) value of 1 nm or less before forming the distributed Bragg reflector

18. The method of claim 13, further comprising polishing the second surface of the substrate by a chemical mechanical polishing process after performing the lapping.

19. The method of claim 17, further comprising polishing the second surface of the substrate using a chemical mechanical polishing process.

20. The method of claim 13, wherein forming the distributed Bragg reflector comprises using ion assisted deposition.